wlr layer shell

Create surfaces that are layers of the desktop

Clients can use this interface to assign the surface_layer role to wl_surfaces. Such surfaces are assigned to a "layer" of the output and rendered with a defined z-depth respective to each other. They may also be anchored to the edges and corners of a screen and specify input handling semantics. This interface should be suitable for the implementation of many desktop shell components, and a broad number of other applications that interact with the desktop.

get_layer_surface(id: new_id<zwlr_layer_surface_v1>, surface: object<wl_surface>, output: object<wl_output>, layer: uint<zwlr_layer_shell_v1.layer>, namespace: string)
Argument
Type
Description
idnew_id<zwlr_layer_surface_v1>
surfaceobject<wl_surface>
outputobject<wl_output>allow null
layeruint<zwlr_layer_shell_v1.layer>
layer to add this surface to
namespacestring
namespace for the layer surface
Create a layer_surface from a surface

Create a layer surface for an existing surface. This assigns the role of layer_surface, or raises a protocol error if another role is already assigned.

Creating a layer surface from a wl_surface which has a buffer attached or committed is a client error, and any attempts by a client to attach or manipulate a buffer prior to the first layer_surface.configure call must also be treated as errors.

After creating a layer_surface object and setting it up, the client must perform an initial commit without any buffer attached. The compositor will reply with a layer_surface.configure event. The client must acknowledge it and is then allowed to attach a buffer to map the surface.

You may pass NULL for output to allow the compositor to decide which output to use. Generally this will be the one that the user most recently interacted with.

Clients can specify a namespace that defines the purpose of the layer surface.

destroy
Type: destructorsince 3
destroy()
Destroy the layer_shell object

This request indicates that the client will not use the layer_shell object any more. Objects that have been created through this instance are not affected.

Argument
Value
Description
role0
wl_surface has another role
invalid_layer1
layer value is invalid
already_constructed2
wl_surface has a buffer attached or committed
Argument
Value
Description
background0
bottom1
top2
overlay3
Available layers for surfaces

These values indicate which layers a surface can be rendered in. They are ordered by z depth, bottom-most first. Traditional shell surfaces will typically be rendered between the bottom and top layers. Fullscreen shell surfaces are typically rendered at the top layer. Multiple surfaces can share a single layer, and ordering within a single layer is undefined.


Layer metadata interface

An interface that may be implemented by a wl_surface, for surfaces that are designed to be rendered as a layer of a stacked desktop-like environment.

Layer surface state (layer, size, anchor, exclusive zone, margin, interactivity) is double-buffered, and will be applied at the time wl_surface.commit of the corresponding wl_surface is called.

Attaching a null buffer to a layer surface unmaps it.

Unmapping a layer_surface means that the surface cannot be shown by the compositor until it is explicitly mapped again. The layer_surface returns to the state it had right after layer_shell.get_layer_surface. The client can re-map the surface by performing a commit without any buffer attached, waiting for a configure event and handling it as usual.

set_size(width: uint, height: uint)
Argument
Type
Description
widthuint
heightuint
Sets the size of the surface

Sets the size of the surface in surface-local coordinates. The compositor will display the surface centered with respect to its anchors.

If you pass 0 for either value, the compositor will assign it and inform you of the assignment in the configure event. You must set your anchor to opposite edges in the dimensions you omit; not doing so is a protocol error. Both values are 0 by default.

Size is double-buffered, see wl_surface.commit.

Argument
Type
Description
anchoruint<zwlr_layer_surface_v1.anchor>
Configures the anchor point of the surface

Requests that the compositor anchor the surface to the specified edges and corners. If two orthogonal edges are specified (e.g. 'top' and 'left'), then the anchor point will be the intersection of the edges (e.g. the top left corner of the output); otherwise the anchor point will be centered on that edge, or in the center if none is specified.

Anchor is double-buffered, see wl_surface.commit.

set_exclusive_zone(zone: int)
Argument
Type
Description
zoneint
Configures the exclusive geometry of this surface

Requests that the compositor avoids occluding an area with other surfaces. The compositor's use of this information is implementation-dependent - do not assume that this region will not actually be occluded.

A positive value is only meaningful if the surface is anchored to one edge or an edge and both perpendicular edges. If the surface is not anchored, anchored to only two perpendicular edges (a corner), anchored to only two parallel edges or anchored to all edges, a positive value will be treated the same as zero.

A positive zone is the distance from the edge in surface-local coordinates to consider exclusive.

Surfaces that do not wish to have an exclusive zone may instead specify how they should interact with surfaces that do. If set to zero, the surface indicates that it would like to be moved to avoid occluding surfaces with a positive exclusive zone. If set to -1, the surface indicates that it would not like to be moved to accommodate for other surfaces, and the compositor should extend it all the way to the edges it is anchored to.

For example, a panel might set its exclusive zone to 10, so that maximized shell surfaces are not shown on top of it. A notification might set its exclusive zone to 0, so that it is moved to avoid occluding the panel, but shell surfaces are shown underneath it. A wallpaper or lock screen might set their exclusive zone to -1, so that they stretch below or over the panel.

The default value is 0.

Exclusive zone is double-buffered, see wl_surface.commit.

set_margin(top: int, right: int, bottom: int, left: int)
Argument
Type
Description
topint
rightint
bottomint
leftint
Sets a margin from the anchor point

Requests that the surface be placed some distance away from the anchor point on the output, in surface-local coordinates. Setting this value for edges you are not anchored to has no effect.

The exclusive zone includes the margin.

Margin is double-buffered, see wl_surface.commit.

Requests keyboard events

Set how keyboard events are delivered to this surface. By default, layer shell surfaces do not receive keyboard events; this request can be used to change this.

This setting is inherited by child surfaces set by the get_popup request.

Layer surfaces receive pointer, touch, and tablet events normally. If you do not want to receive them, set the input region on your surface to an empty region.

Keyboard interactivity is double-buffered, see wl_surface.commit.

get_popup(popup: object<xdg_popup>)
Argument
Type
Description
popupobject<xdg_popup>
Assign this layer_surface as an xdg_popup parent

This assigns an xdg_popup's parent to this layer_surface. This popup should have been created via xdg_surface::get_popup with the parent set to NULL, and this request must be invoked before committing the popup's initial state.

See the documentation of xdg_popup for more details about what an xdg_popup is and how it is used.

ack_configure(serial: uint)
Argument
Type
Description
serialuint
the serial from the configure event
Ack a configure event

When a configure event is received, if a client commits the surface in response to the configure event, then the client must make an ack_configure request sometime before the commit request, passing along the serial of the configure event.

If the client receives multiple configure events before it can respond to one, it only has to ack the last configure event.

A client is not required to commit immediately after sending an ack_configure request - it may even ack_configure several times before its next surface commit.

A client may send multiple ack_configure requests before committing, but only the last request sent before a commit indicates which configure event the client really is responding to.

destroy()
Destroy the layer_surface

This request destroys the layer surface.

Argument
Type
Description
layeruint<zwlr_layer_shell_v1.layer>
layer to move this surface to
Change the layer of the surface

Change the layer that the surface is rendered on.

Layer is double-buffered, see wl_surface.commit.

configure(serial: uint, width: uint, height: uint)
Argument
Type
Description
serialuint
widthuint
heightuint
Suggest a surface change

The configure event asks the client to resize its surface.

Clients should arrange their surface for the new states, and then send an ack_configure request with the serial sent in this configure event at some point before committing the new surface.

The client is free to dismiss all but the last configure event it received.

The width and height arguments specify the size of the window in surface-local coordinates.

The size is a hint, in the sense that the client is free to ignore it if it doesn't resize, pick a smaller size (to satisfy aspect ratio or resize in steps of NxM pixels). If the client picks a smaller size and is anchored to two opposite anchors (e.g. 'top' and 'bottom'), the surface will be centered on this axis.

If the width or height arguments are zero, it means the client should decide its own window dimension.

closed()
Surface should be closed

The closed event is sent by the compositor when the surface will no longer be shown. The output may have been destroyed or the user may have asked for it to be removed. Further changes to the surface will be ignored. The client should destroy the resource after receiving this event, and create a new surface if they so choose.

keyboard_interactivity { none, exclusive, on_demand } 
Argument
Value
Description
none0
No keyboard focus is possible

This value indicates that this surface is not interested in keyboard events and the compositor should never assign it the keyboard focus.

This is the default value, set for newly created layer shell surfaces.

This is useful for e.g. desktop widgets that display information or only have interaction with non-keyboard input devices.

exclusive1
Request exclusive keyboard focus

Request exclusive keyboard focus if this surface is above the shell surface layer.

For the top and overlay layers, the seat will always give exclusive keyboard focus to the top-most layer which has keyboard interactivity set to exclusive. If this layer contains multiple surfaces with keyboard interactivity set to exclusive, the compositor determines the one receiving keyboard events in an implementation- defined manner. In this case, no guarantee is made when this surface will receive keyboard focus (if ever).

For the bottom and background layers, the compositor is allowed to use normal focus semantics.

This setting is mainly intended for applications that need to ensure they receive all keyboard events, such as a lock screen or a password prompt.

on_demandsince 42
Request regular keyboard focus semantics

This requests the compositor to allow this surface to be focused and unfocused by the user in an implementation-defined manner. The user should be able to unfocus this surface even regardless of the layer it is on.

Typically, the compositor will want to use its normal mechanism to manage keyboard focus between layer shell surfaces with this setting and regular toplevels on the desktop layer (e.g. click to focus). Nevertheless, it is possible for a compositor to require a special interaction to focus or unfocus layer shell surfaces (e.g. requiring a click even if focus follows the mouse normally, or providing a keybinding to switch focus between layers).

This setting is mainly intended for desktop shell components (e.g. panels) that allow keyboard interaction. Using this option can allow implementing a desktop shell that can be fully usable without the mouse.

Types of keyboard interaction possible for a layer shell surface

Types of keyboard interaction possible for layer shell surfaces. The rationale for this is twofold: (1) some applications are not interested in keyboard events and not allowing them to be focused can improve the desktop experience; (2) some applications will want to take exclusive keyboard focus.

Argument
Value
Description
invalid_surface_state0
provided surface state is invalid
invalid_size1
size is invalid
invalid_anchor2
anchor bitfield is invalid
invalid_keyboard_interactivity3
keyboard interactivity is invalid
anchor { top, bottom, left, right } 
Argument
Value
Description
top1
the top edge of the anchor rectangle
bottom2
the bottom edge of the anchor rectangle
left4
the left edge of the anchor rectangle
right8
the right edge of the anchor rectangle

Copyright © 2017 Drew DeVault

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